1. Department of Applied Mathematics and Statistics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Nakhon Ratchasima 30000, Thailand
2. Department of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand
3. Department of Mathematics, Faculty of Liberal Arts, Rajamangala University of Technology Rattanakosin, Wang Klai Kangwon Campus, Hua Hin Prachuap Khiri Khan 77110, Thailand